Head up display apparatus for automotive vehicle

ABSTRACT

In a head up display apparatus for an automotive vehicle including a projector unit disposed at the ceiling of the automotive vehicle to project display images and a half-mirror reflector unit for reflecting the projected display images to the driver, the height of the half-mirror reflector unit and the angular position of the projector unit are automatically adjusted according to vehicle speed, so that virtual display images can be appropriately seen by the driver ahead of the half-mirror reflector unit along the driver&#39;s eye direction variable according to vehicle speed, by use of a relatively small half-mirror reflector unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a head up display apparatus for anautomotive vehicle such that display images from a projector isreflected from a transmittable and reflectable optical element(half-mirror) disposed on the dashboard to the driver, so that thedriver can see the reflected display images (e.g. vehicle speed) insuperimposition upon the vehicle outside view.

2. Description of the Prior Art

The same applicant has recently proposed a head up display apparatus foran automotive vehicle which can allowthe driver to simultaneously seethe normal outside view and display images projected from a projectorand reflected from a half-mirror reflector unit. However, since thedriver's eye direction is different between when the vehicle is runningin a city at low speed and when running on a speedway at high speed, itis necessary to adjustably pivot the half-mirror reflector unit so thatthe display image reflected from the reflector unit can correctly bedirected toward the driver. In addition, since the driver's eye positionchanges according to the driver's structure of body or driver's drivingposition, it is also necessary to adjustably move the reflector unit upand down.

Therefore, there exists a problem in that a wide and large half-mirrorreflector unit is inevitably required and therefore the driver'sfrontward field of view is reduced into unsafe condition.

The arrangement of the head up display apparatus for an automotivevehicle will be described in further detail with reference to theattached drawings under DETAILED DESCRITPION OF THE PREFERREDEMBODIMENTS.

SUMMARY OF THE INVENTION

With these problems in mind, therefore, it is the primary object of thepresent invention to provide a head up display apparatus for anautomotive vehicle which can correctly reflect display images related tothe vehicle from the reflector unit of relatively small size to thedriver irrespective of vehicle speed.

To achieve the above-mentioned object, a head up display apparatus foran automotive vehicle according to the present invention comprisesprojecting means, disposed at a ceiling of the automotive vehicle, forprojecting display images; first actuator means, coupled to saidprojecting means, for pivoting said projecting means to adjust aprojection direction of the display images; half mirror reflectingmeans, disposed on a dashboard of the automotive vehicle, for reflectingthe display images projected by said projecting means to a driver;second actuator means, coupled to said half mirror reflecting means, formoving said half mirror reflecting means up and down to adjust a heightof said half mirror reflecting means from the dashboard; sensor meansfor detecting vehicle speed; and control means, coupled to said firstand second actuator means and said sensor means, for controlling anangular position of said projecting means and a height position of saidhalf mirror reflected means according to vehicle speed detected by saidsensor means to automatically form virtual display images ahead of saidhalf mirror reflecting means in a driver's eye direction variableaccording to vehicle speed.

Further, it is preferable that the head up display apparatus furthercomprises third actuator means for tilting said half mirror reflectingmeans upward or downward to adjust an angular position of saidreflecting means so that display images can be correctly reflected fromthe reflecting means to the driver. Further, said control means controlssaid projecting means and said reflecting means in accordance withforward or feedback control method on the basis of table look-up methodin response to detected vehicle speed.

In the head up display apparatus of the present invention, since theheight of the half-mirror reflecting means and the angular position ofthe projecting means are both automatically adjusted according tovehicle speed, the driver can always see virtual display images ahead ofthe windshield on the half-mirror reflecting means in the driver's eyedirection variable according to vehicle speed, in spite of relativelysmall reflecting means.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the head up display apparatus for anautomotive vehicle according to the present invention will be moreclearly appreciated from the following description of preferredembodiments of the invention taken in conjunction with the accompanyingdrawings in which like reference numerals designate the same or similarelements or sections throughout the figures thereof and in which:

FIG. 1 is a diagrammatical side view showing a head up display apparatusapplied to an automotive vehicle, for assistance in explaining problemsinvolved therein;

FIG. 2 is an illustration for assistance in explaining a change indriver's eye direction;

FIG. 3 is a diagrammatical side view, including a block diagram, showingan embodiment of head up display apparatus for an automotive vehicleaccording to the present invention;

FIG. 4 is a partial front view of the display apparatus shown in FIG. 3;

FIG. 5 is an illustration showing an operation panel of the displayapparatus shown in FIG. 3;

FIGS. 6(A) and (B) show examples of height positions of the half-mirrorreflector unit and a display image on the reflector unit;

FIG. 7 is a diagram showing the relationship between vehicle speed anddriver's eye direction;

FIG. 8 is a view for assistance in explaining the positionalrelationship between driver's eye direction, reflector unit height, anddisplay unit projection angle; and

FIG. 9 is a diagrammatical side view showing another modification ofhead up display apparatus for an automotive vehicle according to thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a head up display apparatus for an automotive vehicle,which has recently been proposed by the same applicant. In the drawing,a reflector unit 3 such as a half mirror having appropriate reflectivityand transmissivity is disposed on a dashboard 3 and in front of awindshield 2 within an automotive vehicle. The numeral 4 denotes adriver and 4A denotes a driver's eye. On the other hand, a projectorunit 9 composed of a display device 6 for displaying various informationsuch as vehicle speed, an optical element 7 such as a convex lens forprojecting display images on the reflector unit 3, and a casing forhousing the display device 6 and the optical element 7. The projectorunit 9 is attached to a ceiling 1A of the vehicle 1. The optical element7 serves to form a virtual displayed image 6A produced from the displaydevice 6 at a remote position ahead of the windshield 2 and away fromthe eye position 4A of the driver 4.

Therefore, the driver 4 can see a display image projected from thedisplay device 6 via the optical element 7 and reflected from thereflector unit 3 at a remote position 10m, for instance, away from thedriver's eye in superimposition upon the outside view of the vehicle.

However, as depicted in FIG. 2, when the vehicle is running in a busystreet at low speed, the driver's eye is usually directed toward arelatively near position on the road as shown by the arrow A; and whenthe vehicle is running on a speedway at high speed, the drivers eye isdirected toward a relatively far position on the road as shown by thearrow B.

Therefore, in the display apparatus shown in FIG. 1, it is necessary toadjustably tilt the reflector unit 3. However, since the display imagesshould appropriately be reflected toward the driver even when thereflector unit 3 is tilted upward or downward by manual operationaccording to the driver's eye direction, there exists a problem in thatthe size or the height of the reflector unit 3 should be increased, andtherefore the frontward field of view of the driver is reduced by thereflector unit 3 into unsafe condition. In addition, since the driver'seye position changes according to the driver's structure of body ordriver's driving position, it is also necessary to adjustably move thereflector unit up and down and therefore the virtual display image 6Amoves upward or downward on the reflector unit, thus it being impossibleto see the display image in a fixed position on the reflector unit.

FIG. 3 shows an embodiment of the head up display apparatus according tothe present invention. The apparatus comprises roughly a half-mirrorreflector unit, a projector unit and a control section. Further, thereflector unit is adjustably tilted upward or downward by a firstactuator and moved up or down by a second actuator, and the projectorunit is adjustably pivoted upside or downside by a third actuator allunder control of the control section in response to a vehicle speed.

In FIG. 4, a square half-mirror reflector unit 3 is formed with twopivotal axles 3a and 3b each projecting from the lower side portionthereof. These two pivotal axles 3a and 3b are each inserted into abearing hole 10a or 11a formed respectively at the top end portion ofeach of two support members 10 and 11 to pivotably support the reflectorunit 3 by the two support members 10 and 11. Further, one pivotal axle3b is connected to a first actuator such as micromotor 12 housed in thesupport member 11.

The two support members 10 and 11 are fitted to two guide holes 5a and5b, respectively, formed in the dashboard 5 so as to be movable up anddown. Further, each of the two support members 10 and 11 is formed witha stopper portion 10b or 11b, so that the support members 10 and 11 arenot extracted upward from the dashboard 5.

A female thread is formed in the support member 10 along the axialdirection thereof so as to be engageable with a male thread shaft 13. Asecond actuator such as micromotor 14 fixed to an inner side of thedashboard 5 is connected to one exposed end of the thread shaft 13.

On the other hand, at the ceiling 1A of the vehicle 1, a pivotalprojector unit 9 is attached as shown in FIG. 3. This projector unit 9is fixed to a sector gear 17 rotatable about an axis 16. This sectorgear 17 is in mesh with a pinion gear 19 connected to a third actuatorsuch as micromotor 18 fixed to the ceiling 1A.

In FIG. 3, the control section comprises a first motor driver 20 fordriving a first actuator 12 which tilt the reflector unit 3 so as toface upward or downward; a second motor driver 21 for driving a secondactuator 14 which moves the reflector unit 3 up and down; a third motordriver 22 for driving a third actuator 18 which pivots the projectorunit 3 so that display images are projected at an upside or downsideposition on the reflector unit 3; a controller 23; a vehicle speedsensor 24; and an operation panel 25 mounted on the surface 5c of thedashboard 5.

FIG. 5 shows the operation panel 25 of the apparatus, which comprises anauto/manual selector switch (A/M) 25a; an auto indicator lamp (AUTO)25h; a reflector moving-up button (REF UP) 25b; a reflector moving-downbutton (REF DOWN) 25c; a reflector tilting-upward button (REF UPWARD)25d; a reflector tilting-downward button (REF DOWNWARD) 25e; a projectorpivoting-upside button (PROJ UPSIDE) 25f; and a projectorpivoting-downside button (PROJ DOWNSIDE) 25g.

Further, although not shown, there are provided a first sensor fordetecting an angular position of the reflector unit 3; a second sensorfor detecting a height position of the reflector unit 3; and a thirdsensor for detecting an angular position of the projector unit 9.Furthermore, the controller 23 stores a table which lists preferrableangular and height positions of the reflector unit 3 and preferableangular positions of the projector unit 9 according to detected vehiclespeeds.

The operation of the apparatus will be described hereinbelow; when theauto/manual selector switch 25a is set to auto and therefore the autoindicator lamp 25h comes on, the vehicle speed sensor 24 applies avehicle speed signal to the controller 23. In response to the vehiclespeed signal, the controller 23 selects predetermined data indicative ofappropriate height and angular positions of the reflector unit 3 and anappropriate angular position of the projector unit 9 in accordance withtable look-up method, and generates three control signals to the threemotor drivers 20, 21 and 22 on the basis of the selected data.Therefore, the reflector unit 3 and the projector unit 9 are adjustablymoved to appropriate height and angular positions according to vehiclespeed, until the selected data match height and angular positionsdetected by the three height and angular position sensors (not shown)provided for the three actuators 12, 14 and 18, respectively. In theabove-mentioned operation, the reflector unit 3 and the projector unit 9are controlled to target positions selected from a look-up table inresponse to the feedback values of the three height and angular positionsensors (not shown) by feedback control method. Without being limitedthereto, however, it is also possible to control the reflector unit 3and the projector unit 9 to target positions selected from a look-uptable by direct forward control method. In this control method, thethree actuators such as step motors are directly moved to the targetpositions without providing the above-mentioned three height and angularposition sensors (not shown).

FIG. 6(A) shows an example of the adjusted height position of thereflector unit 3 obtained when the vehicle speed is low; and FIG. 6(B)shows an example of the adjusted height position thereof obtained whenthe vehicle speed is high. Further, the projection direction of theprojector unit 9 is also adjusted by pivoting the unit 9 in linkage withthe movement of the reflector unit 3.

On the other hand, when the auto/manual selector switch 25a is set tomanual and therefore the auto indicator 25h goes off, the reflector unit3 can be moved up or down and tilted upward or downward and theprojector unit 9 is pivoted by depressing the buttons 25b to 25g,irrespective of vehicle speed, so that the driver can adjustably movethe reflector unit 3 and the projector unit 9 in manual operation.

FIG. 7 shows an example of the relationship between the vehicle speedand the driver's eye direction. In this example, when the driver's eyeposition 4A is 1.2 m above the road and the driver drives the vehiclewhile seeing a position on the road 5m ahead of the driver's eye, thedriver's eye downward angle θ₅ is about 13.5 degrees. In contrast withthis, when he drives the vehicle while seeing a position on the road100m ahead of the driver's eye, the driver's eye downward angle θ₁₀₀ isabout 0.7 degrees. Therefore, the difference in driver's eye directionbetween when the driver sees a near position and when he sees a distantposition is about 12.8 degrees.

FIG. 8 shows a height difference 159.5 mm of the reflector unit 3 when ahorizontal distance between the driver eye 4A and the reflector unit 3is 700 mm under the same condition as shown in FIG. 7. This is because avirtual display image projected from the projector unit 9 to thereflector unit 3 should be observed by the driver in front of thewindshield 2 along the driver's eye direction. As shown in FIG. 8, thereflector unit 3 should be adjusted from α to α' or vice versa and theprojector unit 9 should be pivoted so that display images are reflectedfrom a middle portion of the reflector unit 3 to the driver eye 4A. Insummary, the reflector unit 3 is vertically moved up or down and tiltedso as to face downward or upward and further the projector unit 9 ispivoted so that display images are projected to the reflector unit 3, inorder that virtual display images can be displayed appropriately on thereflector unit 3 along the driver's eye direction variable according tovehicle speed.

In the above embodiment, the pivotal angle α (shown in FIG. 8) of thereflector unit 3 is adjusted. However, since the angular differencebetween the two α and α' is relatively small, it is possible toeliminate this angular adjustment of the reflector unit 3. In this case,the first actuator 12 (shown in FIG. 4) can be eliminated.

FIG. 9 shows another modification of the head up display apparatus ofthe present invention, in which display images projected from theprojector unit 9 is reflected by a reflecting mirror 30 pivotable aboutan axle 30 toward the reflector unit 3. In this modification thereflecting mirror 30 is adjustably pivoted by another actuator (notshown) and the pivoted angular position of the mirror 30 is detected bya sensor (not shown).

When the projector unit 9 and an optical system such as a reflectormirror 30 are used in combination, since the visual angle of a projectedimage is not wide, it is particularly preferable to incorporate thefirst, second and third actuators 12, 14 and 18 together in theapparatus.

As described above, in the head up display apparatus of the presentinvention, since the reflector unit and the projector unit are bothadjusted according to vehicle speed, it is possible to automaticallyform virtual display images correctly on the reflector unit in thedriver's eye direction and simultaneously to reduce the size of thereflector unit, thus realizing a head up display easy to see and safe indriving.

What is claimed is:
 1. A head up display apparatus for an automotivevehicle, comprising:(a) projecting means, disposed within a passengercompartment of the automotive vehicle, for projecting display images;(b) half mirror reflecting means, disposed on a dashboard of theautomotive vehicle, for reflecting the display images projected by saidprojecting means to a driver; (c) first actuator means, coupled to saidhalf mirror reflecting means, for moving said half mirror reflectingmeans up and down to adjust a height of said half mirror reflectingmeans from the dashboard; (d) sensor means for detecting vehicle speed;(e) second actuator means, coupled to said half mirror reflecting means,for pivoting said half mirror reflecting means to adjust an angularposition of said half mirror reflecting means so that display images canbe correctly reflected from said half mirror reflecting means to thedriver; and (f) control means, coupled to said first and second actuatormeans and said sensor means, for controlling a height and angularpositions of said half mirror reflecting means according to vehiclespeed detected by said sensor means to automatically form virtualdisplay images ahead of said half mirror reflecting means in a driver'seye direction variable according to vehicle speed.
 2. A head up displayapparatus for an automotive vehicle, comprising:(a) projecting meansincluding an optical system, disposed within a passenger compartment ofthe automotive vehicle, for projecting display images; (b) firstactuator means, coupled to said projecting means, for pivoting saidprojecting means to adjust a projection direction of the display images;(c) half mirror reflecting means, disposed on a dashboard of theautomotive vehicle, for reflecting the display images projected by saidprojecting means to a driver; (d) second actuator means, coupled to saidhalf mirror reflecting means, for moving said half mirror reflectingmeans up and down to adjust a height of said half mirror reflectingmeans from the dashboard; (e) sensor means for detecting vehicle speed;(f) third actuator means, coupled to said half mirror reflecting means,for pivoting said half mirror reflecting means to adjust an angularposition of said half mirror reflecting means so that display images canbe correctly reflected from said half mirror reflecting means to thedriver; and (g) control means, coupled to said first, second, and thirdactuator means and said sensor means, for controlling an angularposition of said projecting means and height and angular positions ofsaid half mirror reflecting means according to vehicle speed detected bysaid sensor means to automatically form virtual display images ahead ofsaid half mirror reflecting means in a driver's eye direction variableaccording to vehicle speed.
 3. The head up display apparatus for anautomotive vehicle as set forth in claim 1, wherein said projectingmeans is disposed at a ceiling of the passenger compartment.
 4. The headup display apparatus for an automotive vehicle as set forth in claim 2,wherein said projecting means is disposed at a ceiling of the passengercompartment.
 5. The head up display apparatus for an automotive vehicleas set forth in claim 1, wherein said control means controls saidprojecting means and said half mirror reflecting means in accordancewith table look-up method on the basis of detected vehicle speed.
 6. Thehead up display apparatus for an automotive vehicle as set forth inclaim 5, wherein said control means controls said projecting means andsaid half mirror reflecting means in direct forward control method. 7.The head up display apparatus for an automotive vehicle as set forth inclaim 5, wherein said first actuator means comprises a sensor fordetecting an angular position of said projecting means and said secondactuator means comprises a sensor for detecting height position of saidhalf mirror reflecting means, to control said projecting means and saidhalf reflecting mirror means in feedback control method.
 8. The head updisplay apparatus for an automotive vehicle as set forth in claim 1,which further comprises an operation panel including an auto/manualselector switch and buttons for manually adjusting a projectiondirection of said projector means and a height and an angular positionof said half mirror reflecting means.
 9. The head up display apparatusfor an automotive vehicle as set forth in claim 2, which furthercomprises an operation panel including an auto/manual selector switchand buttons for manually adjusting a projection direction of saidprojector means and a height and an angular position of said half mirrorreflecting means.